This invention relates to a multiple lumen catheter and more particularly to such a catheter for insertion into a vein of a patient to be used in haemodialysis treatments. The invention also relates to methods for manufacturing the multiple lumen catheter.
Multiple lumen catheters have been available for many years for a variety of medical purposes. It is only in recent years, however, that such catheters have been developed for use in haemodialysis. The general form of multiple lumen catheters goes back to as early as 1882 when Pfarre patented such a catheter in the United States under Ser. No. 256,590. This patent teaches a flexible dual lumen catheter which is used primarily for cleaning and drainage of, for example, the bladder, rectum, stomach and ear. In this type of catheterization, the catheter is introduced into an existing body orifice without the use of any puncturing needle or guidewire.
More recently, a catheter was developed and patented by Blake et al under U.S. Pat. No. 3,634,924. This 1972 patent teaches a double lumen cardiac balloon catheter which is introduced into a large vein and the balloons inflated to control the flow in the vein. The catheter can in fact be placed by using the balloon as sails to move with the blood into or through the heart to a position where the catheter takes up its intended function. This patent uses two lumens and teaches a method of making a tip which involves the use of a plug and a wire which retains the shape of one of the lumens during formation of the tip in a molding technique.
Further patents which teach multiple lumen catheters for general use include the following U.S. Pat. Nos. 701,075; 2,175,726; 2,819,718; 4,072,146; 4,098,275; 4,134,402; 4,406,656 and 4,180,068.
Vascular catheter access by surgical cut-down techniques has been known to the medical profession for many years and, in fact, can be traced back to the 17th century. However, it was only with the introduction of the Seldinger technique in 1953 or thereabouts that a new approach could be used to improve vascular access. This technique was taught in an article published by Seldinger resulting from a presentation made at the Congress of the Northern Association of Medical Radiology at Helsinki in June of 1952. The technique essentially involves the use of a hollow needle to make an initial puncture and then a wire is entered through the needle and positioned in the vessel. The needle is withdrawn and the catheter is entered percutaneously over the wire which is later withdrawn. With this technique it became possible to make less traumatic vascular access and has now become the accepted method of performing access in numerous medical techniques. One of these techniques which has been the subject of much research and development, is haemodialysis.
Haemodialysis can be defined as the temporary removal of blood from a patient for the purpose of extracting or separating toxins therefrom and the return of the cleansed blood to the same patient. Haemodialysis is indicated in patients where renal impairment or failure exists, that is, in cases where the blood is not being properly or sufficiently cleansed, (particularly to remove water) by the kidneys.
In the case of chronic renal impairment or failure, haemodialysis has to be carried out on a repetitive basis. For example, in end stage kidney disease where transplantation of kidneys is not possible or for medical reasons is contraindicated, the patient will have to be dialysed about 100 to 150 times per year. This can result in several thousand accesses to the blood stream to enable the active haemodialysis to be performed over the remaining life of the patient.
Towards the end of 1960, Dr. Stanley Shaldon and colleagues developed, in the Royal Free Hospital in London, England, a technique for haemodialysis by percutaneous catheterization of deep blood vessels, specifically the femoral artery and vein. The technique was described in an article published by Dr. Shaldon and his associates in the Oct. 14, 1961 edition of The Lancet at pages 857 to 859. Dr. Shaldon and his associates developed single lumen catheters having tapered tips for entry over a Seldinger wire to be used in haemodialysis. Subsequently, Dr. Shaldon and his colleagues began to insert both inlet and outlet catheters in the femoral vein and this was reported in the British Medical Journal of Jun. 19, 1963. The purpose of providing both inlet and outlet catheters in the femoral vein was to explore the possibility of a “self-service” approach to dialysis. Dr. Shaldon was subsequently successful in doing this and patients were able to operate reasonably normally while carrying implanted catheters which could be connected to haemodialysis equipment periodically.
Some use was made of a flexible dual lumen catheter inserted by surgical cutdown as early as 1959. An example of such a catheter is that of McIntosh and colleagues which is described in the Journal of the American Medical Association of Feb. 21, 1959 at pages 137 to 138. In this publication, a dual lumen catheter is made of non-toxic vinyl plastic and described as being inserted by cut-down technique into the saphenous vein to the inferior vena cava.
The advantages of dual lumen catheters in haemodialysis is that only one vein access need be affected to establish continued dialysis of the blood, because one lumen serves as the conduit for blood flowing from the patient to the dialysis unit and the other lumen serves as a conduit for blood returning from the dialysis unit to the patient. This contrasts with prior systems where either two insertions were necessary to place the two catheters as was done by Dr. Shaldon, or a single catheter was used with a complicated dialysis machine which alternatively removed blood and returned cleansed blood.
The success of Dr. Shaldon in placing catheters which will remain in place for periodic haemodialysis caused further work to be done with different sites. Dr. Shaldon used the femoral vein and in about 1977 Dr. Uldall began clinical testing of a subclavian catheter that would remain in place. An article describing this was published by Dr. Uldall and others in Dialysis and Transplantation, Volume 8, No. 10, in October 1979. Subsequently Dr. Uldall began experimenting with a coaxial dual lumen catheter for subclavian insertion and this resulted in Canadian Patent No. 1,092,927 which issued on Jan. 6, 1981. Although this particular form of catheter has not achieved significant success in the market-place, it was the forerunner of dual lumen catheters implanted in the subclavian vein for periodic haemodialysis.
The next significant step in the development of a dual lumen catheter for haemodialysis is U.S. Pat. No. 1,150,122 to Martin who produced a catheter which achieved some commercial success. The catheter avoided the disadvantages of the Uldall structure.
A subsequent development is shown in U.S. Pat. No. 4,451,252 also to Martin. This utilizes the well known dual lumen configuration in which the lumens are arranged side-by-side separated by a diametric septum. The structure shown in this patent provides for a tip making it possible to enter a Seldinger wire through one of the lumens and to use this wire as a guide for inserting the catheter percutaneously. Patents to this type of structure followed and include European Patent Application to Edelman published under No. 0 079 719, U.S. Pat. Nos. 4,619,643; 4,583,968; 4,568,329 and U.S. Design Pat. No. 272,651.
All of the above examples of haemodialysis catheters suffer from the disadvantages that they can not be used readily for intravenous injection of liquid medication. A person who is using haemodialysis therapy with a dual lumen catheter will have to receive a needle for intravenous injection when medication of this kind is required. It would be desirable that the catheter not only perform the function of haemodialysis, but also provide a facility for intravenous injection without further puncturing of the patient's veins. It is one of the objects of the present invention to provide such a catheter.
The foregoing problems associated with haemodialysis catheters may on some instances be specific to the treatment. However, the catheter of the present invention, in overcoming the disadvantages of the prior art of renal dialysis catheters, provides a catheter which has utility in other procedures. Accordingly, although the present description is directed to haemodialysis, such use is exemplary and it will be evident that catheters according to the invention may be used for other procedures.